Some devices such as printers use a pressurized air source generated by, for example, an air pumping device to pressurize cartridges to cause a fluid (e.g., an ink) to flow from the cartridge to, for example, a printhead. Additionally or alternatively, some devices employ two cartridges of the same fluid type (e.g., same ink color) to enable replacement of a cartridge without having to interrupt or pause an operation such as printing.